[gimp] Bug 784480 - Clicking on-canvas GUI with a tablet stylus crashes...

[Michael Natterer <mitch src gnome org>]

commit a8bc8d202cdca2bb8832de36362cbeee9f5762e0
Author: Michael Natterer <mitch gimp org>
Date:   Tue Jan 16 21:48:48 2018 +0100

    Bug 784480 - Clicking on-canvas GUI with a tablet stylus crashes...
    
    ...if "Show rulers" is disabled
    
    Add HACK to gimp_display_shell_canvas_realize() that makes sure the
    rulers are always mapped once for each new GimpDisplayShell. This
    seems to magically fix all the crashes.

 app/display/gimpdisplayshell-callbacks.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/app/display/gimpdisplayshell-callbacks.c b/app/display/gimpdisplayshell-callbacks.c
index 1e11b2e..590c491 100644
--- a/app/display/gimpdisplayshell-callbacks.c
+++ b/app/display/gimpdisplayshell-callbacks.c
@@ -116,6 +116,17 @@ gimp_display_shell_canvas_realize (GtkWidget        *canvas,
   gtk_widget_set_size_request (GTK_WIDGET (shell), 0, 0);
 
   shell->xfer = gimp_display_xfer_realize (GTK_WIDGET(shell));
+
+  /*  HACK: remove with GTK+ 3.x: this unconditionally maps the
+   *  rulers, if configured to be hidden they are never visible to the
+   *  user because they will be hidden again right away.
+   *
+   *  For some obscure reason, having the rulers mapped once prevents
+   *  crashes with tablets and on-canvas dialogs. See bug #784480 and
+   *  all its duplicates.
+   */
+  gtk_widget_show (shell->hrule);
+  gtk_widget_show (shell->vrule);
 }
 
 void